Delay unit for a conference audio system, method for delaying audio input signals, computer program and conference audio system

Abstract

A delay unit ( 16 ) for a conference audio system ( 1 ) adapted to delay audio input signals for an adjustable time delay, thereby generating audio output signals, is proposed. The delay unit ( 16 ) comprising a circular buffer ( 17 ); a write pointer (W) to write a sample (S 1 ) of a first input signal to the circular buffer ( 17 ) at a first write position; a read pointer (R) to read a sample from the circular buffer ( 17 ) at a first read position as a sample of a first output signal, whereby the distance between the first write position and the first read position determines a first time delay d old ; a buffer control module adapted to move the write pointer W to a next position after writing and to move the read pointer (R) to a next position after reading; characterized in that the buffer control module is adapted to adjust a second time delay d new by moving the write pointer (W) to a second write position, whereby the distance between the first read position and the second write position determines the second time delay d new .

The invention claimed is:  
     
       1. A delay unit ( 16 ) allocated to a single delegate unit of a conference audio system ( 1 ) having a first audio input signal and a second audio input signal, the delay unit ( 16 ) adapted to delay the first and second audio input signals for an adjustable time delay, thereby generating an audio output signal, the delay unit ( 16 ) comprising
 a circular buffer ( 17 ); 
 a write pointer (W) to write a sample (S 1 ) of the first audio input signal to the circular buffer ( 17 ) at a first write position; 
 a read pointer (R) to read a sample from the circular buffer ( 17 ) at a first read position as a sample of a first output signal, whereby the distance between the first write position and the first read position determines a first time delay (d old ); 
 a buffer control module adapted to move the write pointer (W) to a next position after writing and to move the read pointer (R) to a next position after reading; 
 whereby the buffer control module is adapted to adjust a second time delay (d new ) by moving the write pointer (W) to a second write position to write a sample (S 2 ) of the second audio input signal to the circular buffer ( 17 ) at the second write position, whereby the distance between the first read position and the second write position determines the second time delay (d new ); 
 wherein the buffer control module is adapted to adjust the time delay during a change from the first audio input signal with the first time delay to a second audio input signal with the second time delay. 
 
     
     
       2. The delay unit ( 16 ) according to  claim 1 , characterized in that the second write position is determined by the rule:
   first read position +second delay time =second write position. 
 
     
     
       3. The delay unit ( 16 ) according to  claim 1 , characterized in that the buffer control unit is adapted to zero a location of the circular buffer after reading the sample from the location. 
     
     
       4. The delay unit ( 16 ) according to  claim 1 , characterized in that the buffer control unit is adapted to partly overlap samples of the first signal (S 1 ) and samples of a second signal (S 2 ) in case the second delay (d new ) is smaller than the first time delay (d old ). 
     
     
       5. The delay unit ( 16 ) according to  claim 1 , characterized by a processing unit, which is adapted to fade out the first audio signal. 
     
     
       6. A conference audio system ( 1 ) comprising
 a plurality of delegate units ( 2 ), 
 a control means ( 15 ) for distributing at least one audio signal from at least one sound source to a plurality of the delegate loudspeakers ( 5 ), the plurality of delegate loudspeakers ( 5 ) generating a common audio atmosphere, 
 delay means ( 16 ) operable to add a time delay on the audio signal, 
 whereby the delay means comprise the delay unit according to  claim 1 . 
 
     
     
       7. The conference audio system ( 1 ) according to  claim 6 , characterized in that the time delay is determined based on a distance between the position of the sound source generating the audio signal and the individual delegate loudspeaker ( 5 ) position. 
     
     
       8. The conference audio system ( 1 ) according to  claim 6 , wherein each delegate unit ( 2 ) has a delegate loudspeaker ( 5 ) and a delegate microphone ( 4 ). 
     
     
       9. The conference audio system ( 1 ) according to  claim 6 , wherein each delegate unit ( 2 ) has a delegate loudspeaker ( 5 ). 
     
     
       10. The conference audio system ( 1 ) according to  claim 6 , wherein each delegate unit ( 2 ) has a delegate microphone ( 4 ). 
     
     
       11. The conference audio system ( 1 ) according to  claim 6 , wherein the sound source is one or more delegate microphones ( 4 ). 
     
     
       12. The delay unit ( 16 ) according to  claim 1 , characterized by a processing unit, which is adapted to fade out the first audio signal and to fade in the second audio signal. 
     
     
       13. The delay unit ( 16 ) according to  claim 1 , characterized by a processing unit, which is adapted to fade in the second audio signal. 
     
     
       14. A method for delaying audio input signals for an adjustable time delay, carried out by a delay unit ( 16 ) having a first audio input signal and a second audio input signal and a circular buffer ( 17 ), the delay unit ( 16 ) adapted to delay the first and second audio input signals for an adjustable time delay, thereby generating an audio output signal, the method comprising:
 writing a sample (S 1 ) of the first audio input signal by a write pointer (W) to the circular buffer ( 17 ) at a first write position; 
 reading a sample of the first audio input signal by a read pointer (R) from the circular buffer ( 17 ) at a first read position, whereby the distance between the first write position and the first read position determines a first time delay (d old ); 
 moving the write pointer (W) to a next position after writing and the read pointer (R) to a next position after reading; 
 setting, by the delay unit, the write pointer to a second write position during a change from the first audio input signal with the first time delay (d old ) to the second audio input signal with a second time delay (d new ), whereby the distance between the first read position and the second write position determines the second time delay. 
 
     
     
       15. A non-transitory computer readable medium containing a computer program comprising program-code for carrying out the method according to  claim 14 , when the computer program is carried out on a computer. 
     
     
       16. A non-transitory computer readable medium containing a computer program comprising program-code for carrying out the method according to  claim 14 , when the computer program is carried out on a computer and a delay unit. 
     
     
       17. A non-transitory computer readable medium containing a computer program comprising program-code for carrying out the method according to  claim 14 , when the computer program is carried out on a delay unit.